U.S. Pat. No. 3,079,372 issued Feb. 26, 1963 to Fulkner et al., assigned to Union Carbide discloses a method to divert decomp product (e.g. carbon contaminated polyethylene) out of a reactor. A number of temperature probes along the length of a tubular reactor are rapidly scanned (60 times per second) and if there is a temperature rise above a preset point (about 1000° C.) a valve opens and the contaminated product is vented away from the final product. However the process does not appear to be predictive based on any particular calculation or a mean temperature. Rather it seems 55 to be based on a trial producing decomposition conditions where the temperature is achieved at a single thermocouple.
U.S. Pat. No. 3,781,256 issued Dec. 25, 1973 in the name of Sadee et al., assigned to Stamicarbon N. V. teaches a method to suppress “aerials” an ignition of the reactor contents issued into the atmosphere as a result of a decomposition. Aerials are prevented by introducing water into the reactor contents expelled into the atmosphere within 10 seconds after the reactor safety device has been activated. The patent does not suggest any method for identifying conditions leading to or predicting a decomposition.
U.S. Pat. No. 4,339,412 issued Jul. 13, 1982 to Durand et al, assigned to Societe Chimiques des Charbonnages CdF Chimie, teaches a method to prevent aerials by having gases from a reactor in which a decomposition has occurred, vent into an evacuation pipe in which there is an inert atmosphere. Apparently, the pressure wave from the decomposition travels in excess of the speed of sound and heats air in an evacuation chamber to the ignition point of ethylene. The patent does not teach a method to detect or predict decompositions.
U.S. Pat. No. 4,804,725 issued Feb. 14, 1989 to Kane et al. assigned to BASF Aktiengesellschaft discloses a process where sections of a high pressure tubular reactor are let down after a temperature or pressure exceeds a set point in that section. The contents of the other reactor sections are recycled. This minimizes the amount of reactants, and decomposition material released into the atmosphere. In the patent the control system is for example a commercial measuring and regulating systems (for example AEG Logistat control), by means of which a number of hydraulic valves are controlled. The patent suggests the system is activated when a pressure or temperature is exceeded. The process does not teach a process similar to that of the present invention.
The present invention seeks to provide a method to detect the onset of conditions associated with an increased likelihood in conditions leading to decomposition permitting the conditions in the reactor to be altered to prevent or reduce the likelihood of a decomposition.